Spring detent coupling for telescoped parts



June 5, 1956 1 BAKER SPRING DETENT COUPLING FOR TELESCOPED PARTS Filed March 16, 1955 0.x. (fl-Fromm United States Patent() l SPRING DETENT COUPLING FOR TELESCOPED PARTS John Gordon Baker, Evansville, Wis., assignor to Baker Manufacturing Company, Evansville, Wis., a corporation of Wisconsin Application March 16, 1953, Serial No. 342,625

Claims. (Cl. 285-169) This invention relates to a coupling for extendible structures having telescoped parts and, more particularly to structures having an elongated inner section telescoped within an outer tubular section and slidable outwardly to an extended position in which it is held by a coupling.

The general object is to provide for an extendible structure of the above character a new and improved coupling or joint which holds the inner section securely in the extended position, which is economical in construction and which permits the parts to be telescoped safely and easily.

A more detailed object is to hold the parts in the extended position by detents which project through holes in the outer tube and are yieldably urged into engagement with an abutment on the inner section and to move the detents out of engagement with the inner section by the cam action of cooperating surfaces on the outer tube and on releasing devices which are connected to the de-V tents.

Another object is to cam the detents out of engagement with the inner section by a simple manual turning of the releasing devices.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary elevational view of an extendible mast employing the novel coupling of the present invention.

Fig. 2 is a fragmentary sectional view taken along the line 2--2 in Fig. 1. Y

Fig. 3 is a sectional View taken along the line 3 3 in Fig. 1.

Fig. 4 is a view similar to Fig. 2 showing the parts in a different position.

Fig. 5 is a perspective view of one of the releasing devices. v

For purposes of illustration, the invention is shown in the drawings incorporated in an extendible mast comprising an inner tube smaller than and telescoped within an outer tube 11 so as to slide within the latter from a collapsed or telescoped position to an extended position as shown in Fig. 1. Herein, both tubes are circular in cross section and tapered adjacent their ends as indicated at 12 and 12a (Fig. 2) to prevent the inner tube as it is moved to the extended position from being removed from the outer tube.

To hold the inner tube 10 in the extended position, detents 13 supported by the outer tube 11 are urged inwardly so as to move in behind and engage abutments 14 on the inner tube thus preventing the latter from returning to the telescoped position. The detents project through holes 15 in the outer tube on opposite sides of the latter and may be urged into engagement with the abutments 14 by a generally semi-circular U-shaped bail 16 straddliug the exterior of the outer tube. While the detents 13 may be formed by the inturned ends 17 of the 2,749,153 Patented June 5, 1956 ICC bail proper, it is preferred to use short headed studs having axial recesses 18 in their outer ends to receive the bail ends. The bail is stressed to contract the ends 17 toward each other so that, when the holes 15 are uncovered by the abutments 14 in the outward movement of the inner tube to the extended position, the detents 13 enter behind the abutments. Herein, the latter are the upper edges of notches 19 which are formed in the lower end of the inner tube (Figs. 2 and 3) and are slightly wider than the detents. Thus, in the extended position, the detents are received within the notche locking the inner tube against rotation.

In accordance with the present invention, a releasing device 20 is associated with each of the detents or locking members 13 and, by a novel cam action, cooperates with the outer tube 11 upon turning relative thereto-to retract the detent at least out of locking engagement with the inner tube 10. For this purpose, the releasing devices 20 have follower surfaces 21 engaging cam surfaces 22 on the exterior of the outer tube. ln the present instance, the releasing devices are curved channel members having on the inner side of the web 23 an arcuate surface which, in the inactive position, lies alongside, mates with, and, in the form shown, ts snugly against the outside of the outer tube. Thus, the inner web surface constitutes the follower surface 21 and engages the exterior surface of the outer tube, the latter surface in this case forming the cam surface 22.

To connect each detent 13 to its respective releasing device 20, the detent is received in a centrally disposed hole 24 in the web 23 so that it projects inwardly fromthe middle of the follower surface 21. The head 25 of the detent stud 13 is disposed against the outer side of the web to hold the detent in place with the projecting end of the stud extending beyond the follower surface a distance slightly greater than the combined thickness of the two tubes 10 and 11. With this arrangement, the detents project in through the notches 19 when the releasing devices 20 are in the inactive position as shown in Figs. 2 and 3 and support the inner tube 1t) in the extended position. The releasing devices 2i) are restrained in the inactive position by the spring action of the bail 16. As the releasing devices are turned, by a force suicient to overcome the restraint, through a right angle to the active position illustrated in Fig. 4, the ends of the follower surface 21 ride out on the exterior surface 22 of the outer tube 11 moving the central portion of the web Z3 away from the tube. As a result, the detents 13 are withdrawn from the notches 19 against the spring action of the bail 16 permitting the inner tube to -be telescoped within the outer tube. Preferably, the length of the follower surface 21 is such that, when the releasingdevice 20 is in the active position, the detent 13 still projects into the hole 14 in the outer tube to retain the releasing device in place for turning back to the inactive position. The flanges 26 of the releasing devices project outwardly from the web 23 to provide a linger grip to permit the turning of the devices between the active and inactive positions to be eifected manually.

In erecting the mast, the inner tube 10 is telescoped Within the outer tube 11 and the releasing devices 20 are turned to the inactive position shown in Figs. 2 and 3 in which the arcuate cam and follower surfaces 22 and 21 are concentric. Then the outer tube is mounted in an upright position and the inner tube is slid upwardly toward the extended position. During such sliding the tapered portion 12a of the inner tube engages the detents 13 and force the latter outwardly against the action of the bail 16 and, during the remainder of the upward sliding, the detents are held out by the inner tube. When the latter reaches the extended position, the holes 15 are uncovered permitting the bail to snap the detents in under 3 the lower end of the inner tube. Next, the inner tube is turned until the notches 19 are alined with the detents so that the tube drops down to the locked position shown in Fig. 2.

To disassemble the mast, first one releasingdevice 20 is turned through a quarter revolution to the active position shown in Fig. 4 so that the associated detent 13 is eammed out of its respective notch 19 and then the other releasing device is turned in a similar manner. With both detents withdrawn, the inner tube lil is unlocked and may again be telescoped within the outer tube 11.

It will be observed that the joint of the present invention is comparatively inexpensive to manufacture since it requires only a few parts and, at the same time, it locks the tubes 10 and 11 securely in the extended position. The cooperation of the spring action and the mating curved surfaces positively restrains the releasing member in the inactive position. With this joint, the tubes may be collapsed merely by turning the releasing devices 2i) to the active position to cam the detents I3 out of engagement with the inner tube. Such turning may be effected easily by hand without the use of a tool to pry the detents out. Further, since the releasing devices hold the detents in the retracted position, they may be turned one at a time leaving the worker with one free hand to support himself.

I claim as my invention:

1. In an extendible structure, the combination of, an outer cylindrical tube, an inner tube telescoped within an end portion of said outer tube and shiftable outwardly to an extended position, diametrically disposed holes extending through said end portion and spaced from the end of said portion so as to be uncovered by the inner end of said inner tube in the outward movement of the same to said extended position, two members, one disposed adjacent each of said holes and each having a lateral projection extending into its respective hole, and a generally U-shaped bail straddling said outer tube and having inturned ends engaging said members and urgingsaid projections inwardly so as to enter behind the end of said inner tube as the latter moves outwardly to said extended position, said members having arcuate inner surfaces normally lying snugly against the outer surface of said outer tube and positively restrained in place thereagainst by said bail while serving, when the members are turned about the axes of said projections by a force suicient to overcome said restraint, as cams to retract said projections out from behind the inner end of said inner tube.

2. In an extendible structure, the combination of, a

tube of arcuate cross section, an inner member telescoped in an end portion of said tube and shiftable outwardly to an extended position in said tube portion, said tube having angularly disposed holes extending through said end portion and spaced from the end of said portion so as to be uncovered by an abutment on said member in the outward movement of the latter to said extended position, a plurality of supports, one disposed adjacent each of said holes and each having a curved surface normally lying snugly against the outer surface of said tube,

abutment and to restrain said supports in place against said outer surface while permitting the supports to be turned about the axes of said projections, when said restraint is overcome, thereby to cam the projections out of engagement with the abutment.

3. An extendible structure comprising, an outer tubc having an arcuate cross section and two angularly disposed holes extending through an end portion thereof and spaced from the adjacent end of the tube, an inner tube telescoped within said end portion and shiftable outwardly from a telescoped position to an extended position in which said holes are uncovered by notches in the inner end of said inner tube, two detents, one projecting into each of said holes, a support for each of said detents, and a resilient member having its ends connected to said detents and yieldably urging the same into said holes so as to enter said notches as said inner tube moves outwardly to said extended position and prevent the inner tube from returning to said telescoped position, said supports having arcuate inner surfaces normally lying snugly against the exterior surface of said outer tube and positively restrained in place thereagainst by said resilient member, while operable when the supports are turned about the axes of said detents by a force sutlicient to overcome said restraint to cam the latter out of said notches and permit said inner tube to be returned to said telescoped position.

4. In an extendible structure, the combination of, a tube having an inner and au outer surface and having holes through opposite sides, a resilient bail straddling said tube and having end portions turned inwardly and rcceived in said holes, said bail tending to collapse to project the ends of said portions inwardly beyond the inner surface of said tube, and members journaled on said inturned portions and having surfaces coacting with a surface on the exterior of said tube to positively resist turning of said member and when said resistance is overcome during turning of the member to cam the end portion outwardly at least to said inner tube surface.

5. In an extendible structure, the combination of, an outer tube, an inner member telescoped within an end portion of said tube and shiftable outwardly to an extended position, a hole extending through said end portion and spaced from the adjacent end of said tube so as to be uncovered by an abutment on said member in the outward movement of the same to said extended position, an element disposed adjacent said hole exteriorly of said tube and having a part projecting laterally into the hole, means engaging said element and yieldably urging said part inwardly so as to enter behind the inner end of said member as the latter moves outwardly to said extended position, and cam and follower surfaces on said tube and v said element coacting to positively resist turning of the a lateral projection on each of said supports extending 60 inwardly through said holes to enter behind said abutment as said members moves outwardly to said extended position, and means resiliently urging said supports against said tube to hold said projection in engagement with said latter and operable when the element is turned relative to said tube by a force sufiicient to overcome said resistance to shift the part out from behind said abutment.

References Cited in the file of this patent UNITED STATES PATENTS 1,026,093 Johnson May 14, 1912 2,232,824 Maher Feb. 25, 1941 2,395,234 ySchlueter Feb. 19, 1946 

